Dust collector



Jan. 22, 1952 G. A. Bor-:SGER

DUST COLLECTOR 5 Sheets-Sheet l Filed June 1, 1949 G. A. BOESGER DUSTCOLLECTOR Jan, 22, 1952 3 Sheets-Sheet 2 Filed June 1, 1949 INVENTOR.66ans ,4. 505565@ Jan. 22, 1952 G. A. Box-:sGr-:R 2,583,039

DUST COLLECTOR Filed June 1, 1949 5 sheets-sheet s INVENTOR. foes A.505565@ BY 22;

l TTORNEYS Patented Jan. 22, 1952 DUST COLLECTOR George A. Boesger,North Olmsted, Ohio, assignor to The W. W. Sly Manufacturing Company,Cleveland, Ohio, a corporation of Ohio Application J une 1, 1949, SerialNo. 96,426

(Cl. 18S-61) 7 Claims.

This invention relates to improvements in dust collectors, that is tosay apparatus for removing dust from dust laden air, either for thepurpose of purifying the air or for the purpose of recovering values inthe dust, or both.

One form of apparatus employed for this purpose embodies a series ofporous fabric bags through which the air is drawn and by which the dustis ltered out. In the use of such equipment the pores of the bags tendto become clogged after a period of time, the length of which dependsupon the particular service. It is necessary therefore to interrupt theoperation of the apparatus at intervals in order to shake the dust loosefrom the bags or otherwise remove it.

In accordance with the present invention the operation of the apparatusis continuous, and the bags are cleaned one at a time by a reversecurrent of airfwhich flows in a direction opposite to that of the maincurrent, due to the fact that the pressure in the reverse current isgreater than that in the main current.

One of 'the objects of the invention is the provision of means forcleaning the porous fabric bags of a dust collector one by one by meansof a travelling Vcarriage to which is connected a conductor that directsthe reversely flowing air through the bags.

Another object is the provision of means for employing atmospheric airfor the reverse current.

A further object is the provision of means for selecting by a simpleadjustment either atmospheric air or air at greater than atmosphericpressure for the reverse current flow.

Still another object is the provision of electrical meansforautomatically reversing the direction of movement of the travellingcarriage as it reaches the ends of its path of travel.

Another object is the provision of means for stopping the operation ofthe apparatus completely in the event that the traveling carriage Shouldfail to make a complete traverse within a predetermined period of time.

Y.Other objects and features of novelty will appear as I proceed withthe description of that embodiment of the invention which, for thepurposes of thejpiesent application, I have illustrated in theaccompanying drawings, in which lig;y l a front elevational view ofapparatus which'- may be employed in carrying out the invention, theforward wall of the casing being removed to better illustrate theinvention, and the view being taken substantially along the line I-I ofFig. 2.

Fig. 2 is a side elevational View of the saine with a side Wall of thecasing removed.

Fig. 3 is a horizontal sectional view taken substantially on the line3--3 of Fig. 2.

Fig. 4 is a fragmental horizontal sectional view on a larger scale, theview being taken substantially on the line 5 4 of Fig. 2.

Fig. 5 is a detail sectional view of a valve for selecting reversecurrent air either from atmoshere or from the discharge of the blower,and

Fig. 6 is a wiring diagram.

In the drawings the apparatus is disclosed as embodying a substantiallyair-tight casing having a rear wall It, a front wall II, side walls I2and i3 and a cover or roof I. The casing is divided into a dust chamberI5 and a clean air chamber I3 by a transverse partition wall I'I. A dusthopper I8 of conventional form communicates with the dust chamber I5.The transverse wall Il is provided with a series of narrow verticalopenings |9 which are bordered by forwardly extending flanges 26 thatsurround the openings and the forward edges of which lie in a commonplane.

In the illustrated embodiment there are three series or tiers of narrowporous fabric bags 2l, the bags of each series being disposed side byside and their forward open ends being connected by any suitable meanswith the transverse wall I'I surrounding the several openings I9, Itshould be understood of course that less than or more than three tiersof bags may be employed in any given unit as the requirements of aparticular installation may dictate. As is common in the art each of thebags is provided with an internal Wire frame, not shown, to prevent thecollapse of the bag and assist in supporting it.

Connected with the dust chamber l5 there is an intake pipe 23 for dustladen air. In the wall I I at the front of the casing there is anopening communicating with a conductor 24 which leads to the intake of ablower 25 driven by means of a shaft 2B from an electric motor 21. Theblower exhausts through a conductor 28. When the apparatus is inoperation blower 25 maintains a sub-atmospheric pressure in clean airchamber I6 and in dust chamber I5, whereby dust laden air enters theapparatus through pipe 23, is filtered by the bags 2i, passes into theclean air chamber I6 and is exhausted through the conductor 2li, blower25 and exhaust conductor 28. The dust which is removed and falls fromthe bags 2| collects in the hopper I t,

Running over the flanges 20 in close contact therewith so as to minimizeair leakage, there is a diaphragm 30 mounted on a travelling oarriage.At its upper and lower ends this carriage has wheels 3|, 32 which runupon tracks 33, 34 extending across the casing from one side to theother. Midway of its length this diaphragm carries an air-tight housing35, and at the upper and lower ends this housing is connected byconductors 35 with similar housings 3l' and 38 also mounted on thediaphragm. Through the diaphragm opposite each or the housings S5, 31and 38, there is an elongated opening 35, Fig. 4, which is adapted toregister at times with each of the openings i through the transversepartition wall and hence with the respective bags.

Housing 35 may include an angular connection 5) from which there extendsa flexible tubular conductor or horse di. The opposite end of thistubular conductor extends into a hollow bridge member i2 mounted in thecasing wall l! and providing a passage for air into the tubularconductor lli from a tubular conductor 4| extending downwardly on theoutside of the casing. The bridge member .12 is mounted in the frontwall H near the central point of the horizontal travel of diaphragm 35.

An endless chain or cable 45 extends across the chamber l5 in front ofthe partition wall Il. It runs over a sheave 55 mounted on wall I2,preferably outside the casing, and over a pulley il mounted on the shaftof a reversible electric motor a which is supported on the wall i3outside the casing. rThe two runs of this endless connector may extendthrough small openings in the side walls of the casing. The ends of thechain or cable are secured to the sides of some part of the travellingcarriage, as for example the housing 35. Obviously, when the motor 68turns in one direction the diaphragm 39 will travel toward the left, andwhen it turns in the opposite direction the diaphragm will travel towardthe right.

In order to reverse the current through the motor i3 when the diaphragmreaches one end of its travel, the diaphragm may carry opposed .it

projections which are adapted to strike the operating levers on limitswitches 5l, 52 mounted on the respective casing walls l2 and I3.

As a further control I provide an electric timer mechanism designatedgenerally by the reference numeral which is so constituted and soconnected in the electrical system of the apparatus that it will openthe circuits of both of the motors 2i and 45 in the event that thediaphragm carriage fails to travel through a complete reciprocation backand forth within a period of time that is normally more than suihcientfor the purpose.

At the bottom of the conductor 62 outside the casing I provide a Yconnection 55, one branch 55 of which is open to atmosphere, see Fig. 5.

The other branch 5l is connected by a conductor 58 with the exhaust pipe28 from blower 25. In the Y connection 55 there is mounted a shalt 55which constitutes the pivot for a gate valve G0 that is operable by acrank 5I to assume either the full line position which closes offconductor 58 or the broken line position indicated at 5U which closesofi the atmosphere branch 56. This valve may also be adjusted tointermediate positions if desired for mixing atmospheric air withexhaust from blower 25 so as to regulate the pres sure of the reverseair above atmospheric pressure. In addition to this selective or mixingvalve I provide a valve 52 of the butterfly type in conductor i2 on thedownstream side of the Y connection by means of which the volume of airflowing to the diaphragm passages may be controlled` The simplifiedwiring diagram or" Fig. 6 shows provision for the supply of power tooperate the carriage and fan motors 4S and 21, respectively, as well asto control the operation of these motors from a source of 3-phase,alternating current, electrical energy represented by the power supplylines Ll, L2 and L3. These power supply lines are connectible with thewires G5, 55 and 51 by means of a suitable disconnect switch or circuitbreaker, generally designated 58. Wires 65, 55 and 63' are respectivelyconnectible with the leads 55, lil, and 'il for the motor 48 undercontrol of a relay, generally designated l2, to thereby eiiect movementof the carriage in one direc tion. The leads 59, 1f.) and 'H of themotor 48 are also selectively connectible respectively with the powerlines 5l, 55 and 55, respectively, under control of a second relay,generally designated 73, for eiecting movement of the carriage in theopposite direction. Control of the energization of the relays lf2 and'I3 is effected jointly through the previously mentioned limit switches5l, 52 and the timing mechanism 53 in a l .anner about to be described.The fan motor 2'! is energized under control of a relay 'f4 either inconjunction with energization of the carriage motor 48 or independentlythereof, as may be desired.

rEhe nature of the wiring circuit illustratedin Fig. 6 will best beunderstood from a description of the mode of operation. For convenience,let it be assumed that the carriage is at a point intermediate the twolimit switches 5| and 52 and that the fan 21 is to be automaticallyenergized upon energization of the carriage motor 48. The operator willnrst place the selector switch l5 in the position marked Auto, asindicated in Fig. 6, and move the switch ESto circuit closing position.He next momentarily depresses the start button 'i6 thereby completing acircuit extending from the Wire S5 through a wire 11, the now depressedswitch l5, wire 18, normally closed stop switch I9 and wires 85, 8l toone terminal of the coil 32 of a holding relay generally designated 83.The circuit is completed from the other terminal of the coil 83 throughWire 34 and a wire 85, the latter being connected with the main powerline 6'1.

The resulting energization of relay 53 closes its contact B6. Thisprovides a holding circuit about the start switch 1S so that the lattermay now be released. This holding circuit extends from the wire 'Hthrough the Wires 87, 88, contact 89 of the timing device 53, wire 95,the now closed contact S6 of relay 83, the circuit continuing throughthe wires 9|, 92, 78, stop switch '19, Wire 8i, coil 52, and wires 84,55 to the wire 61. A circuit is also completed from wire 9| through theselector switch 'i 5, to one terminal of the coil of the fan relay 14,the circuit being completed to the wire 5'.' from the other terminal ofthis coil through the wires -94 and 85. Therefore, in addition toprovidinga holding circuit, the energization of relay 83 has alsoenergized the relay 74, thereby moving its contacts to closed positionand thus connecting the wires 55, 56 and 6? with the leads 95, 95 and 5lfor the motor 21, so that the fan is placed in operation. The fact thatthe relay S3 is energized is indicated by illumination of a signal lamp98, the circuit therefor extending from the wire through a wire 99 toone terminal of the lamp and from the other terminal of the lamp througha wire I to a connection with the wire 34.

The limit switches 5| and 52 are such that their movable contacts arerespectively urged to one circuit closing position, as shown in Fig. 6,and are moved from that position to the otherposition thereof only whenthe carriage engages the carriage motor 48 is energized for rotation inthe roller on the end of the actuating arm of the corresponding switch,the switches returning to their initial position as soon as the carriagemoves from contact therewith. Therefore, with the carriage intermediatethe switches, the latter will be disposed as shown in Fig. 6.Consequently, the forward relay 12 is energized through a circuit eX-tending from the wire 55 through wires 11, 81, 88, contact 88, wire 30,contact 86 of relay 83, wires 9|, |0| and |02 to one terminal of thecoil |03 of the relay 12. This circuit continues from the other terminalof the coil |03 to a wire |04 and through a contact |05 of the relay 13,when the latter is deenergized, to a wire |03, thence through themovable contact element |51 of the 15 switch 12 to a wire |08 which isconnected to one terminal of the coil 09 in the timing mechanism 53. Thecircuit is completed from the other terminal of the coil |09 through awire ||0 which is connected to the wire 85 and hence to the power wire61. The energization of coil |03 of the relay 12 moves its contacts tocircuit closing position thereby connecting the motor leads 59, and 1|with the wires 85, 56 and 51 so that the direction which moves thecarriage towards the switch 52.

When the carriage has engaged and actuated the switch 52, the contact|01 thereof is moved from the position shown, thereby opening thecircuit between the wires |05 and |08 deenergizing the coil |03 of therelay 12 and consequently deenergizing the carriage motor 48 so that thecarriage stops. The fan motor 21, however, remains in operation. Thejust-mentioned operation of the switch 52has, however, closed a circuitenergizing the reverse relay 13, this circuit extending from the closedcontact of the holding relay 82 through the wires 9| and Il to oneterminal of the coil of the relay 13. This circuit continues from theother terminal of the coil through a wire H2, the contact |01 of switch52 which is now in engagement with the terminal connected to the wireH2, thence to a wire ||3, through the movable contact i4 of the switch5|, to and through a wire ||5 which is connected to movable contact I3of the timer 53. The circuit is completed from the contact I5 through awire ||1, which is connected to the wire 85, and through the latter tothe power wire 61. The coil is therefore energized so that the relay 13moves its contacts to circuit closing positions for energizing the motor48 in the reverse direction since the power wires 55, 55 and 51 are nowconnected with the motor leads 1|, 10 and 69, respectively. Also, theenergization of the relay 13 has moved the contact |05 thereof from itsposition shown in Fig. 6 to a position engaging the contacts illustratedimmediately therebelow. This opens the circuit between the wires l|011and |05 preventing improper or inadvertent operationof the forward relay12 and at the same time the contact |05 provides a holding circuit forthe relay 13, this holding circuit extending from the wire ||2 throughthe Contact |05 to the wire ||8 Awhichl is connected to the wire l|3 andhence,

through the previously described circuit, to the power wire 61.

Consequently, when the contact |01 of switch 52' returns. to itsposition illustrated in Fig, G, 70

4which happens as soon as the carriage begins moving to the right, theenergization of the rewill therefore continue to move towards the switch5|, that is to the right as viewed in Fig. 6, until the carriage engagesand operates the switch 5|. Upon such engagement, contact ||4 is movedfrom its position shown in Fig. 6 thereby opening the holding circuittherethrough for the reverse relay 13 deenergizing the latter andthereby deenergizing the motor 48.

The deenergization of the relay coil restores the contact |05 to itsposition as shown in Fig. 6, thereby restoring the circuit forenergization of coil |03 of relay 12, as was previously described, withthe result that the motor 48 is again energized for rotation in adirection moving the carriage towards the switch 52. Since thisenergization of the relay 12 and hence of the motor 48, is not dependentupon circuits extending through the left-hand contacts of the limitswitch 5|, as viewed in Fig. 6, no holding circuit is required tomaintain the motor in operation after it moves from engagement with theswitch 5|. Moreover, since the actuation of the switch 5| haddeenergized the coil of relay 13, the holding circuit through theContact |05 thereof was broken and this relay cannot be reenergizedagain until the carriage reaches and operates the switch 52, since theenergizing circuit for the coil of relay 13 is open at the contact |01.

It will be apparent, therefore, that in the normal operation of thedevice the carriage continuously moves backwardly and forwardly betweenthe limit switches 52 and 5| with the fan 21 in continuous operation.Provision is made in the circuit, however, for stopping the motor 08 ofthev carriage in the event it fails to complete one completereciprocatory movement within a predetermined length of time and it isfor this purpose that the timing mechanism 53 is provided.

For the purposes of this disclosure it is sufiicient to note that thetiming mechanism 53 comprises a motor I9, which through reductiongearing drives a shaft which is provided with two arms |20 and |2|.These arms are normally locked together for movement with the shaft butthe timing of the device may be set by pulling one of the arms outwardlyand turning it to a new setting thereby changing the angular spacingbetween the arms which represents the selected time interval. Uponrestoring the adjusted arm to its inward position, the arms are againlocked together. A ratchet wheel |22 is loose upon the motor shaft. Thiswheel has a stop pin |23 which is normally held against one of the arms,such as |20, by a reset spring, not shown, disposed between the wheeland the motor shaft. Adjacent the ratchet wheel |22 is a pawl member |24which is mounted for limited pivoting movement and longitudinal movementby means of a iixed pin within a slot of the pawl member, the latterbeing urged to a position in which it is free of engagement with theratchet wheel |22, and of the contact H6, by a tension spring |25. Thispawl member |24 is adapted to be engaged with the ratchet wheel |22 byenergzation of the previously mentioned coil |09 and the pawl member isadapted, as presently described, to open the cir. cuits extendingthrough the contacts S9 and H6 by engaging and moving the latter, whichare connected for movement together, in the event the coil |09 is notdeenergized within the pre-` selected period of time.

The motor ||9 is energized through a circuit extending from the wire |02through a wire |25 to one terminal of the motor, the other terminal4being connected by a wire |21 to the wire |15 sox arm |2| has engagedthe pin |23.

that the circuitl is completedthroughthe conf tact IIGandthewiresll'land fiato the `power wire 67. Consequently, the-motori |9isenergizedunder control of the holding relay B31and remains in continuousoperation so longas-theholding relay remains energized. This wouldnormally producev rotation of( theV ratchet ,wheelV |22- to? gether withthe arms |20l and; |2|. However, it will be observed that, with Atheswitches disposed as shown in Fig. 6, the coil |89 is also energized.This moves pawl member |211 into engagement with the ratchetwheel- |22holding thelatter from rotation so that the arms |20 and 1,|2|-1o. taterelative thereto. As soon as the'carriage engages and operates-theswitch v52;however, the circuit through the contact |91 thereof, bywhich the-coil |89 of the timer is energized, isv broken therebydeenergizing the coil releasing the pawl member from the ratchet wheelso that the latter is reset to engage-the pin |23 with the arm |28 bymeans of the springnot shown. This begins Va new timing cycle.

Preferably the angular space between Athe arms |20, |2| is so set thatthe time requiredl to rotate the arm |2| into engagement with the pin|23 on the ratchet wheel |22, when the latter is held stationary bymeans of the pawl member |24, .exceeds slightly the time required for acomplete reciprocation of the carriage from the switch 52 to the switchand back again to switch 52. Consequently, in normal operation of thedevice, the carriage by its movements will deenergize coil |99 of thetiming mechanism once during veach complete reciprocation, and hencebefore arm |21 engages pin |23, so that the circuits through thecontacts 89 and ||6 of the mechanism remain closed. However, if thecarriage should failto make a complete reciprocation within thepredetermined time, the switch 52 is not actuated for deenergization ofthe coil |09 before the When Athis engagement occurs, the continuedrotaton of the arm |2| tends to produce a partial rotation of theratchet wheel |22, thereby -forcing the pawl member |24 downwardly, asviewed in Fig. 6, so that this member engages and opens the contacts ||6and 89. Opening of these contacts breaks the holding circuit for therelay 83 and the energizing circuit for the motor ||9 of the timingapparatus, thereby deenergizing the car.- riage motor 48, the fan motor21, and the-timing mechanism 53.

To restart the apparatus, after it has'been stopped by operation of thetiming mechanism, it is necessary to again depress the start switch T8and, if the condition which caused the timing mechanism to operate hasnot been corrected so that the carriage again fails to make a completereciprocation in the predetermined time. the apparatus will again stopas just described. When, however, the carriage completes itsreciprocation within the predetermined time, the timing mechanism doesnot operate to stop the device but instead is automatically reset, aspreviously described, for a new timing operation.v Stopping of theapparatus may be eiiected at any desired time by momentarily depressingthe rstop switch 'iii thereby breaking the circuits through relays 83and 'i4 andlthat one of relays 12 and lI3 then energized,

In some instances it is desirable to have the fan 2l operate withoutreciprocation of the carriage. For this type of operation ihe selectorswitch l5 is moved from the position shown in Fig.:6 toal positionengaging. the unwired contactmarked 65 interrupts the carriage travel.

Manuall This opens thek circuit for` energization ofv the vfan motor 21through the holdingrelay 83. Thefanmotor may, however,- now beenergizedby` operation of a manual start button 5 28 which closesacircuit fromthe power-wire 65 through the .wires- Il and 8l to the .wire 93 thencethrough the coil of the fan relay 'I4 and the Wires 94 and 85 to thepower wire 61. Consequently, the fan relay 'i4 is energized energizingthe fan motor 2l. Itwill be understood that the fan motor 21 will remainenergized in this manner only so long as the start switch |28 is held incircuit closing position, but if desired the start switch |28 may beprovided with a conventional ferrule or collar for maintainingthe'latter closed if desired. This featurebeing conventional is notillustrated and, likewise, for simplicity conventional protectivedevices such as current overload switches, vfuses, and the like, havebeen omitted.

The operation will be evident from the above description of theapparatus. As indicated in Fig. 3 dust-laden air will flow through thechamber l5 and pass from the outside to the inside of the various bags2|. The dust is filtered out by the porous fabric of these bags and theclean air emerges from the open ends of the bags into the clean airchamber i5, passing thence through the blower 25 and out through theclean air exhaust 28. This flow of air is prevented however 3,3 throughthose bags which are masked off' by the diaphragm 39. As shown in Fig.v4 there are three such bags, the center one of which is registered withthe opening 39 through the dia,- ,phragm Reverse air passes throughthelatter bag as indicated by the arrows-of that ligure.

The pressure of this reverse air is greater than that prevailing in thechamber I5, becauseits pressure is at least atmospheric whereas that inchamber l5 is sub-atmospheric. The reverse air, .1,9 the pressure ofwhich may be regulated to suit particular requirements as previouslyexplained, .dislodges the dust which is collected on the exteriorsurfaces of the bag causing it to drop downwardly through the chamber I5into the hop- Del i8.

The carriage on which is mounted the diaphragm 3i) travels slowly acrossthe casing causing opening 39 to register with each of the bags 2| oneafter another, so that each one is cleaned for every traverse of thecarriage from one side of the casing to the other. The iiexibleconductor or hose ,4| is longl enoughto follow the carriage throughoutits travel. it being understood that the bridgingconnection 421s locatednear the mid-point of travel. The blocking oi by the diaphragm 38 of abag on either side of 'the bag being cleaned, leaves .a space on eachside of the latter bag which is occupied by more or less dead air, sothat the dust dislodged readily ,to falls instead of beingcarried atonce, against another bag.

IThe traverse of the carriage back'and forth con'inues indenitely solong as the control switch 63 is closed unless some diilculty ariseswhich If thisv occurs timer 53 functions to lower the contacts ||6 and89, whereupon all circuits vare broken andcur.-

rent ceases to ow through motors 21 and 48 and the timer motor .i I9.Signal lamp 98 goes out and the apparatus .as a whole ceases to functionuntil thediiiiculty is corrected.

Having thus described my invention, I claim;

l. In a dust collector, a casing, a wall dividing said casing into adust chamber and a clean air ,76 chamber, a plurality of porous bags insaid dust chamber arranged side by side in a horizontal series withtheir open ends attached to said wall in communication with openingsthrough the wall, an inlet to said dust chamber for admission ofdust-laden air, a blower having its intake connected with said clean airchamber, a diaphragm in the latter chamber having an opening adapted toregister with said wall openings one at a time, means for traversingsaid diaphragm back and forth from one end of said wall to the other,and means for maintaining communication between said diaphragm openingand air outside the casing comprising a flexible tubular conductorconnected to the diaphragm at one end and communicating with an openingthrough the casing at its opposite end.

2. A dust collector as dened in claim 1, wherein said means fortraversing said diaphragm comprises an endless exible connectorextending transversely of said casing parallel to said dust wall, bothruns of said connector passing through openings in a side wall of thecasing, a rotary driving member for said endless connector disposedexteriorly of said casing wall, and automatic means for reversing thedirection of rotation of said driving member as said diaphragm reacheseither end of its travel.

3. A dust collector as dei-ined in claim 1, wherein said means fortraversing said diaphragm comprises an endless flexible connectorextending transversely of said casing parallel to said dust wall, areversible electric motor disposed outside said casing and operativelyconnected to said endless connector for driving it in either direction,limit switches on both side walls of said casing, and means moving saiddiaphragm for operating one or the other of said limit switches as thediaphragm reaches the limit of its travel in either direction, andelectrical connections controlled by said limit switches for reversingthe current through said motor.

4. In a dust collector, a casing, a wall dividing said casing into adust chamber and a clean air chamber, a plurality of porous bags in saiddust chamber arranged side by side in a horizontal series with theiropen ends attached to said wall in communication with openings throughthe wall, an inlet to said dust chamber for admission of dust-laden air,a diaphragm in said air chamber having an opening adapted to registerwith said wall openings one at a time, means for traversing saiddiaphragm back and forth from one end of said wall to the other, ablower having its intake connected to said clean air chamber forsubjecting the latter to sub-atmospheric pressure, a flexible tubularconductor connected with the opening in said diaphragm and extendingoutside of said casing, the exterior portion of said conductor having aY connection, one branch of which leads to atmosphere and the otherbranch of which is connected with the discharge 10 of said blower, andvalve means for bringing one or the other of said branches intocommunication with said conductor.

5. In a dust collector, a casing, a wall dividing said casing into adust chamber and a clean air chamber, a plurality of porous bags in saiddust chamber arranged side by side in a horizontal series with theiropen ends attached to said wall in communication with openings throughthe wall, an inlet to said dust chamber for admission of dust-laden air,a diaphragm in said clean air chamber having an opening adapted toregister with said wall openings one at a time, means for traversingsaid diaphragm back and forth from one end of said wall to the other, ablower having its intake connected to said clean air chamber forsubjecting the latter to sub-atmospheric pressure, a flexible tubularconductor connected with the opening in said diaphragm and extendingoutside of said casing, the exterior portion of said conductor having aY connection, one branch of which leads to atmosphere and the otherbranch of which is conected with the discharge of said blower, and valvemeans for apportioning the flow of air from said branches into saidconductor.

6. A dust collector as defined in claim 5, comprising means in saidconductor exterior of said casing but on the downstream side of saidvalve for regulating the flow of air to said diaphragm.

7. A dust collector as defined in claim 1, wherein said means fortraversing said diaphragm comprises an endless flexible connnectorextending transversely of said casing parallel to said dust wall, meansoperatively connected with said endless connector for driving it ineither direction, a timer having a period somewhat greater than the timerequired for a complete traverse of said diaphragm, and electricalcontrol means, set in motion by said timer upon failure of saiddiaphragm to complete a traverse within said timer period, forinterrupting the operation of said blower.

GEORGE A. BOESGER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,538,292 Lindsay May 19, 19251,949,540 Hammond Mar. 6, 1934 2,318,395 Hornbrook May 4, 1943 2,391,534Yerrick et al. Dec. 25, 1945 2,476,942 Arnold July 19, 1949 2,507,335Donohue May 9, 1950 FOREIGN PATENTS Number Country Date 548,298 FranceOct. 17, 1922

